In 3GPP (3rd Generation Partnership Project) Long Term Evolution (LTE), study is being conducted that the following information (RAN (Radio Access Network) Context Data), which is the information concerning a mobile station that performs inter base station handover, is transferred from a source base station (source eNB) to a target base station (target eNB), when the mobile station performs inter base station handover (abbreviated “HO”). (For example, see non-Patent Document 1).
1. Qos profiles (QoS profiles of the SAE(System Architecture Evolution) bearers)
2. AS configuration (RLC (Radio Link Control) Window Size, etc.)
In addition, when the source base station is transmitting downlink data, the source base station performs data forwarding which transfers unsent data to the target base station.
The mobile station that has moved to the target cell accesses the target base station via Random Access Channel (RACH), which is an uplink channel, to acquire Timing Advance (TA), provided for uplink synchronization, and uplink scheduling information from the target base station. After that, the mobile station adjusts transmission timing according to the acquired TA and transmits “HO Confirm”, which is a control signal for notifying that the mobile station has performed handover to the target base station, at allocated time and frequency.
In LTE, study is being conducted also on DRX (Discontinuous Reception: intermittent reception) control of a mobile station in the RRC (Radio Resource Control)_Connected state (see Non-Patent Document 1).
A base station performs DRX control of entire mobile stations in a cell that the base station manages, and a mobile station performs the discontinuous reception at a periodic interval (also called “DRX cycle” or “DRX period”) specified by the base station. A DRX cycle (DRX period) includes a reception period during which data is continuously received and a non-reception period during which no data is received, as shown in FIG. 18.